PROJECT SUMMARY Treatment for type 1 diabetes (T1D) involves life-long daily injections of insulin to ensure tight metabolic control. However, recent studies have shown that diabetic patients still have residual functional ? cells within their pancreas and hence therapeutic interventions that could recover and/or regenerate ? cell quantity and function would have a profound impact on these patients. A promising approach to preserve and regenerate ? cells is to deliver mesenchymal stem cell (MSC)-based therapies directly to the pancreas. MSCs can release immunomodulatory, angiogenic, anti-inflammatory, anti-apoptotic and anti-fibrotic factors into their surrounding microenvironment to modulate the immune system as well as stimulate the regeneration of damaged tissues; these paracrine factors are released either in a soluble form or within extracellular vesicles (EVs). Studies have shown that both parent MSCs (i.e. a cellular therapy) and MSC-derived EVs (i.e. a cell free therapy) can improve the survival and function of islets. Unfortunately, the clinical translation of MSC-based therapies for the treatment of diabetes has been sub-optimal, predominantly due to majority of MSCs and EVs getting trapped in the lung and reticuloendothelial system, respectively, following conventional intravenous (IV) injection. Hence, in the present proposal, we will: (i) investigate a novel approach using pulsed focused ultrasound (pFUS) to gently shake and ?prime? the pancreas to release chemicals which can attract and retain MSC-based therapies that are delivered directly into the gland by intra-arterial (IA) injection and (ii) determine which source and type of MSC-based therapy is best suited to regenerate and protect the diabetic pancreas. In Aim 1, we will investigate the biological effects of pFUS, which is a clinically available technology, on the pancreatic gland, individual pancreatic islets and different sources of MSCs. In pilot studies, we have found that soundwaves can not only stimulate pancreatic islets and MSCs, but they can also induce the expression of chemoattractants (i.e. cytokines, trophic factors, and cell adhesion molecules) in the pancreas; the latter will help to facilitate the homing, permeation and retention of MSC-based therapies to struggling islets within the diabetic pancreas. In Aims 2 (parent MSCs) and 3 (MSC-derived EVs), we will evaluate the effect of MSC-based therapies derived from different sources (i.e. bone marrow, adipose tissue and umbilical cord) on regenerating the diabetic pancreas when they are given directly into the gland via IA injection, before and after ?priming? the pancreas with pFUS. To achieve these aims, we developed a technique to deliver therapeutics directly into the pancreas, via its arterial blood supply, which is designed to simulate what Interventional Radiologists can do using endovascular techniques. In addition, we will use a novel device called ExoTIC to isolate MSC-derived EVs with high purity and yield for our studies. Together, we hope to determine the optimal parameters (i.e. MSC-based therapy, delivery route and pFUS parameters) that can be clinically translated for the treatment of T1D patients.